1. Field
The present disclosure relates to in-ground (and above-ground) vinyl swimming pool installations and other constructions wherein a flexible sheet member needs to be attached to a rigid support structure. More particularly, the disclosure concerns a technique for retaining a flexible sheet member to a support structure inside corner configuration.
2. Description of the Prior Art
By way of background, vinyl swimming pools are conventionally constructed with a flexible water-tight liner made from heavy duty vinyl. For an above-ground vinyl swimming pool construction, the bottom of the liner is supported by a suitable base made from packed sand or the like. The sides of the liner are supported by a rigid sidewall made from components such as metal, plastic or wood panels. For an in-ground vinyl swimming pool construction, the liner is supported within an excavation whose shape provides a desired perimeter configuration and depth contour of the swimming pool. The bottom of the excavation typically comprises a vermiculite cement or packed sand base. The sides of the excavation are typically lined with a rigid side wall. The side wall can be constructed from panels made of steel, plastic, fiberglass or wood. Alternatively, the side wall can be constructed as a formed concrete wall or from concrete blocks.
For both above-ground and in-ground vinyl swimming pools, the upper peripheral edge of the liner usually comprises a bead that is secured in a track at the top of the side wall. Such pools generally also have a stair system and possibly a “swim-out” bench system, each of which may be fabricated using various materials. For in-ground vinyl swimming pools, commonly-used stair and bench system materials include steel, molded plastic and poured concrete. For above-ground vinyl swimming pools (which may have an inside stair system, an outside stair system, or both), molded plastic is usually the material of choice, but other materials may also be used.
For both stair and bench systems, there will be least one inside corner where the bottom edge of a vertical component (e.g., a stair riser) intersects the rear edge of a horizontal component (e.g., a stair tread or pool bottom). The liner typically needs to be attached to the inside corner(s) in order to prevent unsightly (and potentially unsafe) wrinkling and bulging. This is particularly the case near the top of a stair system where there may only be a few inches of water to hold the liner in place. In addition to holding the liner in place, the liner attachment needs to be releasable to allow for the liner to be replaced in the future.
As shown in FIG. 1, the preferred technique used for many years to retain a vinyl swimming pool liner at the inside corner of a stair or bench system has been to form loops “L” on the back of the liner that slide over a fiberglass retaining rod “R.” The retaining rod “R” is secured to the underlying stair or bench structure using metal spring clips “C.” The spring clips “C” are deformable so that they can be inserted between a gap “G” that is provided at the inside corner tread/riser intersection. In some cases, clip insertion can be expedited by loosening one or more bolts that hold together the stair or bench structure (if constructed as an assembly). This allows the gap “G” to be temporarily enlarged in order to make it easier to insert the spring clips “C.” Following insertion, the spring clips “C” return to their original configuration, thereby holding the liner firmly against the inside corner. One drawback of the rod/clip technique is that the outline of the retaining rod “R” is visible through the liner following installation. Some individuals find this visually unattractive. The rod/clip technique is also difficult or impossible to use when installing replacement liners because it requires the spring clips “C” to be inserted between the step riser and step tread after they have been cemented into place and have no flexibility to move and allow the spring clips to slide between them. This often necessitates the application of adhesives to retain the replacement liner. Such adhesives may cause accelerated deterioration of the liner. The use of adhesives also makes future liner replacements difficult.
More recently, a bead and track system has been used for corner retention areas. As shown in FIG. 2, this prior art system incorporates a liner lock extrusion “E” that is mounted between the riser and tread components when the stair or bench system is assembled. The extrusion “E” has an upper channel that is substantially U-shaped. A small retaining flange “F” is formed at the upper edge of one of the channel sidewalls to partially close off the channel opening. A liner bead “B” is attached in a suitable manner (e.g., using R.F. welding) to the back side of the liner. To secure the liner to the inside corner, the liner bead “B” is inserted into the channel, where it is trapped in place by the retaining flange “F”. This method works satisfactorily from a mechanical standpoint, but has several problems. First, the cost of the stair or bench system is high because of the assembly process required. Second, the extrusion must be separately fabricated or purchased from a third party, thus further increasing costs. Third, the extrusion gets sandwiched between two components of the stair or bench system. In some cases, the extrusion will be made from aluminum and the stair or bench system components will be sheets of zinc-coated steel. This may lead to corrosive galvanic action. In other cases, the extrusion will be made from plastic. Such extrusions are subject to wear and may become brittle over time.